Method of substrate temperature control and method of assessing substrate temperature controllability

Abstract

A method of substrate temperature control for plasma processing apparatus in which a substrate which is being held on a substrate holder in a process chamber is being processed, and He gas is passed through the gap between the substrate and the substrate mounting surface during the processing of the substrate, the substrate temperature is controlled by the thermal transfer characteristics of the gas and the substrate is cooled to the prescribed temperature, and the pressure of the He gas is preset by a pressure setting part 50 a , the actual pressure is measured with a pressure gauge 49 , and the gas flow rate is controlled in such a way that the measured pressure becomes equal to the set pressure by a pressure control valve 46 . Furthermore, the substrate temperature controllability is assessed by monitoring the gas flow rate with a substrate temperature controllability assessment part 50 b.

What is claimed is:  
     
       1. A method of assessing a substrate condition of a substrate, comprising the steps of: 
       delivering a heat transfer gas to a control device including an exhaust valve and a pressure control valve;  
       supplying a set pressure value to the pressure control valve;  
       closing the exhaust valve so that all of the heat transfer gas passing the pressure control valve is delivered to a gap between the substrate and a substrate mounting surface of a substrate holder;  
       measuring the pressure of the heat transfer gas which is flowing in the gap between the substrate and the substrate mounting surface of the substrate holder;  
       supplying the measured pressure to the pressure control valve;  
       automatically controlling the flow rate of the heat transfer gas with the pressure control valve on the basis of a difference between the set pressure value and the measured pressure such that the measured pressure of the heat transfer gas becomes equal to the set pressure value and the flow rate corresponds to a leakage rate of the heat transfer gas; and  
       assessing a state of the gap between the substrate and the substrate mounting surface on a basis of a comparison of the heat transfer gas flow rate with a standard value.  
     
     
       2. The method of assessing a substrate condition according to  claim 1 , wherein the substrate holder includes an electrostatic chucking stage, and temperature controllability of the substrate is assessed by assessing a state of electrostatic force between the substrate and the electrostatic chucking stage.